If any member of the Dave Matthews Band needed to die in exchange for the group's longevity, it had to be LeRoi Moore.

Surely it couldn't have been Boyd Tinsley, the muscle-bound violinist, frequently seen sawing and galloping around stage right in tight, ripped jeans and leather vests, his pearly smile gleaming forward from his oil-slick skin. And it couldn't have been Carter Beauford, the instructional video of a drummer surrounded by a sea of splash cymbals and rack toms, blowing big, pink bubbles of gum as his four limbs kept complicated time. Over the last two decades, dancing-at-the-knees bassist Stefan Lessard adapted ingeniously to Beauford's demands, tweaking his tone to match the subtlety and thunder of the drummer to his side. And if, like Matthews, you front a band named for yourself, chances are the brand would do best if you stuck around.

But LeRoi Moore—a woodwind and whistle player born in Durham but schooled in the early '80s jazz clubs of Virginia—most often lurked in the shadows of stage left, his heavy eyes frequently hidden by futuristic sunshades. His long dreadlocks and propensity for shirts and pants of solid, muted colors created a camouflage, allowing Moore the illusion of anonymity in rooms of 20,000 or so cheering strangers. Moore was integral to the band's best music, sure, his deep baritone sweeps providing a necessary complement to Matthews' too-tinny guitar and Tinsley's flamboyant showmanship. Despite Moore's virtues, there are always other saxophonists who too can stand in the shadows for a nightly fee.

That lesson served as the chief takeaway from the band's 2008 summer tour. Between concerts in northern Virginia and Charlotte, Moore sustained broken ribs and a punctured lung when he crashed an ATV on his Charlottesville farm. He slipped into a coma. That was a Monday; by the start of Tuesday's North Carolina show, Jeff Coffin—the versatile horn man of Béla Fleck & the Flecktones and a longtime Dave Matthews Band collaborator—had taken Moore's place until, as one news post put it, "LeRoi has made a recovery."

That didn't happen. During the next six weeks, Moore was in and out of the hospital. Not long after returning to his second home in Los Angeles for rehabilitation, Moore suffered an embolism and died suddenly. That night, a few miles away, the Dave Matthews Band played its scheduled show at Los Angeles' Staples Center, opening with the fatalistic tune "Bartender." Matthews then told the crowd that his old friend and the band's co-founder had passed earlier in the day. They played 19 more songs, toured for the next month and have since released two albums. 2009's Big Whiskey & the GrooGrux King depicted Moore on the cover; this year's Away from the World is their most vibrant and necessary album in more than a decade. Their output since 1998, it's worth noting, has been both limited and largely dismissible.

But even Matthews, who has frequently espoused the epicurean ideals of seizing the day and living how you'd like, has started to wonder about the relevance of his own band, or how something that's devoured more than 20 years of his life (and that of his audience, too) can remain relevant.

"I try to justify what we do with our lives, and that question becomes more difficult to answer," Matthews, a 45-year-old father of three, told Rolling Stone in September. "I feed this beast that I'm part of, and in some ways I worry that it loses legitimacy."

This issue isn't limited to the Dave Matthews Band; it is rock 'n' roll's greatest pandemic. Only 60 years after its origins, rock music and its multifarious subdivisions remain a playground of dinosaurs or, more generously, acts who have ignored their own decline to maintain, unlike Moore, the illusion of relevance.

Some of rock's best songs address this exact topic: When has a band outlasted its invitation? What comes next? Neil Young famously asked the question; his recent non-archival output suggests that maybe the test shouldn't have been quite so multiple-choice.

Whether for the revenue that their sound generates, for the egos that their fame feeds, or simply for the love of making music, bands struggle with letting go. There's likely a rock band breaking up somewhere in a fit of discontent as you read this sentence, but a successful ensemble is reluctant to quit. Rather, they senesce into a relationship resembling a marriage that has settled for cooperation, where the parties involved maintain the semblance of accord simply because it's what they know or because, well, who else is going to take care of the kids? It's not necessarily comfortable, but it is more comfortable than unfamiliarity. Then they ask us to pay attention.

Consider Keith Richards and Mick Jagger, Liam and Noel Gallagher, Eddie Van Halen and David Lee Roth: Despite public animus, those pairs maintained their partnerships because maintaining a brand is much easier than starting a new one. When's the last (or first) time you've listened to Liam Gallagher's Beady Eye?

The examples of bands that have, for better and worse, perpetuated a name and a brand long after the expiration date might appear to have passed are legion and pervasive. The Band made an ill-advised decision to continue without the frail-voiced Richard Manuel or irksome leader and brilliant songwriter Robbie Robertson. Though their music replicated a cycle of short lives and sudden deaths, the Norwegian black metal pioneers Mayhem have been at it for two decades, after the death not only of vocalist Dead but also their founder and the genre's head henchman, Euronymous. Provided they finish their rumored sixth LP, the Wu-Tang Clan will have released a third of its output with Ol' Dirty Bastard long since cremated.

But what's worse is when bands continue after one member's death and take their success as an ostensible guarantee of immortality: The Rolling Stones, for instance, soldiered along without Brian Jones, the co-founding guitarist who died in a swimming pool less than a month after announcing his departure from the band. Yes, their decision was the right one. Though Jones played on some of the Stones' best records, he'd all but checked out by the time they cut Let It Bleed. Without him, they released two consecutive masterworks (1971's Sticky Fingers and 1972's Exile on Main St.) before becoming the paragon of bands that don't know when or how to stop.

With a sporadic succession of stand-ins and special guests, the Stones have creaked along for 40 more years, issuing records that have ranged from decent to disastrous and launching bloated tours and box sets that thrive more on spectacle than sound. They remain, at best, a nostalgia act—a curiosity that's survived from rock's antediluvian phase, like a Late Cretaceous coelacanth in an impossibly complicated aquarium. That's why parents—and their children or grandchildren, eager to witness living history, in lights—continue to consume the band's high-price tickets. At worst, they are an infinite punchline.

Metallica has suffered the toil of a similar prognostication. The California dudes recorded a triptych of increasingly ambitious thrash classics as a quartet with bassist Cliff Burton, who died when the band's tour bus crashed in 1986. 1988's ...And Justice for All and 1991's eponymous black album don't match the records before them in urgency, but they did push Metallica squarely into superstar status. Metallica, for instance, spent nearly 300 weeks, or more than five years, on the Billboard 200; it is acknowledged as one of the best-selling metal albums ever. Metallica subsequently toured stadiums, headlined Woodstock '94 and issued a tyrannosaurus-sized box set.

And that's exactly when they should have quit. Instead, they plowed ahead into a monolith of embarrassments, from the bad-enough-to-warrant-a-sequel Load and group therapy sessions captured for a documentary to the solo-less St.Anger and a cred-building/breaking collaboration with Lou Reed. Early in its career, Metallica played to throngs of fans on massive Monsters of Rock tours; one has to expect that they're just years away from launching a Zombies of Rock series.

Metallica is still a band, but they've been finished for two decades.

Between 1996 and 2005, I saw the Dave Matthews Band about 50 times. Their music introduced me to Neil Young and Sonic Youth, the Kronos Quartet and Aimee Mann. Their music introduced me to my best friend and an online community that, as a high school kid in rural North Carolina, opened an extremely wide window on the world. Their music even introduced me to writing about the arts; my high school's newspaper generously published my sycophantic but brief review of the band's two-night stand in Raleigh during the spring of 2001, as well as a photo of Matthews with his arm around the author. In every sense and without hesitation, I can say the Dave Matthews Band redirected my life.

So when the Dave Matthews Band plays in Raleigh next week, I'll be there. My college friends will be there, too. They want to tailgate, or at the very least, grab a beer when the concert's curfew calls. I'll likely oblige. I'm excited for the show. I haven't heard these songs—the sprawling "Seek Up," the skittering "Say Goodbye," the sexy "Crush"—in years. I reckon that they'll remind me of myself, sitting alone in my childhood bedroom and staring at my speakers as their best album, the rock music crucible called Before These Crowded Streets, taught me about dissonance and dynamics and deliverance.

I'll probably think a lot about LeRoi Moore, too. At least for me, he remains a member of the Dave Matthews Band, hiding out in the shadows, breathing deep to push the bass notes of "Bartender" through the arena. In that song, the one the band played in Los Angeles just before they announced Moore's death in 2008, Matthews pleads for a little help: "If all this gold should steal my soul away/ Oh, dear mother of mine/ Please redirect me."

Some part of me wishes they'd taken those words as a cue after Moore's death. In an ideal world, they would have decided that with one of them gone, they were done. Rather than bet on immortality and soon land on idiocy, like the Stones, they would cash out of their own Big Touring Machine and find other funnels with different names for their creativity. In essence, they would honor what they'd started by ending it on time and with dignity.

But if that had happened, where would I go—or, for that matter, many of the other 20,000 folks from which Moore surely would have hidden next week in Raleigh—for my memories?

No matter how much they once meant, I'm reluctant to follow a childhood love down the rabbit hole of fading relevance, hoping every few years that the new record is going to be better than embarrassing. Hopefully, that's not an assessment that the Dave Matthews Band is forced to make in retrospect, either.